How much warning can be expected before the tornado hits is the third consideration. How long the damage will keep people from their day-to-day lives is the fourth step. The formula for arriving at the final number is a bit complex, giving more value to the probability of an event happening and how severe it could be.
There is also a financial value for local leaders to get involved with assessing risks in the region and doing that job accurately, Hosmer said. Once the information is gathered, it will be used to justify the need for federal grants in a continually shrinking pool of federal money.